Weird Wildlife Wednesday: Siphonophores
Instead of looking at an individual species, this week’s topic is a fascinating class of animals called siphonophorae.
Video Credit: Nautilus Exploration Program
This video captures a recent discovery by the Nautilus Live expedition. [An awesome project that publishes gorgeous HD videos of their deep sea explorations online]
Siphonophores may look look like a single animal, but they are actually each a colony of physiologically linked organisms called zooids . These zooids begin life together, from an egg, and function together with highly specialized roles to create a single entity. There are two types of zooids, medusae and polyps. Medusae are jellyfish and a common example of a solitary polyp is a sea anemone. Polyps also form colonial animals of their own, notably colonial coral.
The role of each zooid type is unique and completely dependent on the rest of the organisms in the colony. Polyps feed but cannot swim, while nectophores, a type of medusae, swim but cannot eat. This dependence is what differentiates a siphonophore from a colony of animals and also from a multicellular organism. Siphonophores are more interdependent than ants in a colony, but zooids are more independently functional than the cells of a plant.
Certain species of siphonophores like the Giant Siphonophore can grow up to 40m (still not converting for you), which is longer than even the blue whale. It is nowhere near the largest animal however, the diameter of most siphonophores is usually only a few inches.
The most familiar example of a siphonophore is a Portuguese man o’war. Commonly mistaken for a jellyfish, this most venomous species doesn’t propel itself in the water at all, but floats at the surface on a gas bubble, called pneumatophore, that also acts as a bit of a sail.